SaaS (software as a service) is software you use over the internet and pay for by subscription, instead of buying and installing it once.
The provider runs the servers, ships updates continuously and usually charges monthly or yearly per user, per account or by usage.
Most new web products for businesses are SaaS, from invoicing tools to analytics.
Why it matters for a launch
Subscription revenue makes growth compound, which is why metrics like MRR and churn matter so much for SaaS makers.
Read more: How to launch a SaaS product